Users of the World Wide Web can choose among a number of commercial Web search engines when performing information seeking activities. The decision of a user to select one engine over another may be based on a range of factors that include reputation, familiarity, retrieval effectiveness, and interface usability.
Switching from one search engine to another is typically very easy. For example, a user may type in the address of another search engine, select a bookmark that references the other search engine, search using the name of the other search engine, and so forth. When users permanently or even temporarily switch from one Web search engine to another, this may cause a revenue loss to one Web search engine and a revenue gain to another Web search engine. Thus, Web search engine providers are very interested in minimizing switches from and maximizing switches to their search engine.